1. Field of the Invention
The present invention relates to a camera having an attitude detecting function and arranged to perform control according to the attitude of the camera.
2. Description of Related Art
FIG. 11 shows a single-lens reflex camera. The single-lens reflex camera is provided with a main mirror 104 for guiding an object image, i.e., information on an object to be photographed, from a photo-taking lens 103 to an eyepiece 107 and a light measuring sensor 108 through a viewfinder optical system 106. The main mirror 104 is swingably disposed between the photo-taking lens 103 and a shutter 110 which is arranged to control an exposure amount in exposing a film 111 to the object image coming from the photo-taking lens 103. When the camera measures light while the camera user is observing the object before taking a shot, the main mirror 104 is set at an observing position, i.e., at an entrance position within a photo-taking optical path where the object image from the photo-taking lens 103 can be guided to the eyepiece 107.
A central part of the main mirror 104 is arranged to be a half mirror. A submirror 105 is swingably carried by the main mirror 104. A part of the object information from the photo-taking lens 103 passes through the half mirror part of the main mirror 104 to be guided to a focus detecting device 112 through the submirror 105.
To prevent the object image from the photo-taking lens 103 from being eclipsed by the main mirror 104 and the submirror 105 in taking a shot, the mirrors 104 and 105 are swung upward into a retracted position which is located outside of the photo-taking optical path.
After completion of an exposure, the main mirror 104 and the submirror 105 are moved back to the observing position to permit observation of the object and light-measuring and focus-detecting actions for the next shot.
The main mirror 104 is urged to move downward by a spring (not shown). When a member which is pushing the main mirror 104 upward is released from the pushing action after completion of an exposure, the main mirror 104 is caused by the urging force of the spring to swing downward back to the observing position. Following the downward motion of the main mirror 104, the submirror 105 also moves back to the position shown in FIG. 11.
According to the procedures for the sequence of actions of the camera to be performed after an exposure, the light-measuring and focus-detecting actions, etc., for the next shot are allowed to be performed after the lapse of a predetermined period of time (mirror stabilization time) from the commencement of downward movement of the mirrors 104 and 105 from the retracted position to the observing position. The predetermined period of mirror stabilization time is set at a length of time found through tests to be required after the commencement of the downward movement of the mirrors from the retracted position to the observing position and before they cease to bounce on stoppers to lay at rest.
However, since each of the mirrors has a certain amount of mass, the length of time to be set as the mirror stabilization time varies with the posture or attitude of the camera. In other words, the mirror stabilization time varies according to the relation of the urging direction of a spring force to the direction of gravity. In view of this, a camera disclosed, for example, in Japanese Laid-Open Patent Application No. HEI 6-74766 is arranged to have the mirror stabilization time selectable from among a plurality of periods set according to the various attitudes of the camera.